In FIG. 12 and FIG. 13, an electronic component 1 of interest to the present disclosure is shown by a perspective view and a sectional view, respectively. The electronic component 1 includes a chip-shaped electronic component body 2. The electronic component body 2 has a cuboid shape in which an outside shape is defined by four side surfaces 3, 4, 5 and 6 and two end surfaces 7 and 8.
An internal conductor of the form appropriate to a function of the electronic component 1 is disposed inside the electronic component body 2. Herein, a coil component is exemplified as an electronic component 1. Therefore, as shown in FIG. 13, a coil conductor 9 is disposed inside the electronic component body 2. In addition, in FIG. 13, the coil conductor 9 is schematically shown in a drawing by a symbolic expression. Further, when the electronic component 1 is a coil component, the electronic component body 2 is formed from, for example, magnetic ceramics such as Ni—Zn—Cu-based ferrite, and has a laminate structure, not shown in detail, provided by a plurality of ceramic layers 10. A direction of lamination of the laminate structure is directed to a lateral direction in FIG. 13.
External electrodes 11 and 12 electrically connected to the above-mentioned coil conductor 9 are formed on the electronic component body 2. At least parts of the external electrodes 11 and 12, that is, surface layers of the external electrodes 11 and 12 are provided by plating films 13 and 14, respectively, formed by electrolytic plating, in an example shown in the illustration. In order to form such plating films 13 and 14, a seed electrode serving as a starting point of plating growth are formed so as to constitute a ground of the plating films 13 and 14 as described in, for example, Japanese Patent Laid-open Publication No. 11-67554.
The seed electrode includes end surface underlying electrodes 15 and 16 formed on end surfaces 7 and 8, respectively, of the electronic component body 2, and a plurality of side surface underlying electrodes 17 and a plurality of side surface underlying electrodes 18 formed so as to extend in parallel with the end surfaces 7 and 8, respectively, in the side surfaces 3 to 6.
The end surface underlying electrodes 15 and 16 are formed by applying the electroconductive paste onto the end surfaces 7 and 8 and firing the paste.
The side surface underlying electrodes 17 and 18 are formed in an electronic component body 2 obtained undergoing a firing step by having screened an electroconductive paste film to become the side surface underlying electrodes 17 and 18 on specific ones of a plurality of ceramic green sheets to become a plurality of ceramic layers 10 which provide the laminate structure of the electronic component body 2.
Further, a plurality of side surface underlying electrodes 17 are electrically connected to one another, and the side surface underlying electrodes 17 are electrically connected to the end surface underlying electrode 15 with a connection conductor 19. Similarly, a plurality of side surface underlying electrodes 18 are electrically connected to one another, and the side surface underlying electrodes 18 are electrically connected to the end surface underlying electrode 16 with a connection conductor 20. The connection conductors 19 and 20 have the effect of enhancing a probability of causing a state of electric continuity to the seed electrode by contact of a conductive medium in performing electrolytic plating by a barrel plating method. The connection conductors 19 and 20 are formed, for example, by providing a through hole for specific ones of a plurality of ceramic green sheets to become a plurality of ceramic layers 10 which provide the laminate structure of the electronic component body 2, and filling the hole with the electroconductive paste.
In the electronic component 1 described above, noting end edges 21 and 22, respectively, of the plating films 13 and 14 providing surface layers of the external electrodes 11 and 12, each of the positions of the end edges 21 and 22 is determined depending on how far each of the plating films 13 and 14 grows along the side surfaces 3 to 6. In the degree of plating growth along these side surfaces 3 to 6, that is, a dimension of plating growth L, not a start point of plating growth but an end point of plating growth is important.
As an element of determining the above-mentioned dimension of plating growth L, there is a charge amount (current value×plating time) applied during electrolytic plating. Accordingly, conventionally, the charge amount applied for achieving a desired dimension of plating growth L has been set for every product to be produced, and the set charge amount has been applied to perform electrolytic plating during producing the product. However, even in the same product, there may be cases where such variations that the dimension of plating growth L varies with change in production lot have occurred between production lots.
It is desired that the dimension of plating growth L does not vary as far as possible. The reason for this is that the variations in dimension of plating growth L between a plurality of electronic components 1 can lead to variations in characteristics between a plurality of electronic components 1. For example, when the electronic component 1 is a coil component, if the dimension of plating growth L is too large, a degree of interference between a magnetic flux formed by the coil and the plating films 13 and 14 increases, and may have the effect on the characteristics of the electronic component 1. Further, variations in dimension of plating growth L may pose a defective appearance.
The variations in dimension of plating growth L are not limited to one which can occur between a plurality of electronic components 1. In one electronic component 1, as results of variations in dimension of plating growth L, linearity of the end edges 21 and 22 of the plating films 13 and 14 is impaired, and the end edges 21 and 22 may be typically formed in the shape of a wave, leading to a defective appearance.